Background: Exercise capacity is a well-defined marker of outcome in congenital heart disease. We analyzed seventeen cardiovascular magnetic resonance (CMR) derived parameters and their correlation to exercise capacity in patients with Ebstein's anomaly (EA).
Methods: Fifty-four surgery free patients, age 5 to 69 years (median 30 years) prospectively underwent CMR examination and cardiopulmonary exercise testing (CPET). The following volume/flow parameters were compared with peak oxygen uptake as the percentage of normal (peakVO2%) using univariate and multivariate analysis: right and left ventricular ejection fraction (RVEF and LVEF), the indexed end-diastolic and end-systolic volumes (RVEDVi, RVESVi, LVEDVi, and LVESVi), the indexed stroke volumes (RVSVi and LVSVi), the total normalized right and left heart volumes; the total right to left heart volume ratio (R/L-ratio). The indexed antegrade flow (ante), indexed net flow (net) as well as cardiac index (CI) in the aorta (Ao) and pulmonary artery (PA) were used.
Results: RVEF (R2 0.2788), indexed flow PA net (R2 0.2330), and PA ante (R2 0.1912) showed the best correlation with peakVO2% (all p < 0.001) in the univariate model. Further significant correlation could also be demonstrated with CI-PA, LVEF, LVSVi, Aorta net, RVESVi, and Aorta ante. Multivariate analysis for RVEF and indexed net flow PA revealed a R2 of 0.4350.
Conclusion: Functional CMR parameters as RVEF and LVEF and flow data of cardiac forward flow correlate to peakVO2%. Evaluation of the indexed net flow in the pulmonary artery and the overall function of the right ventricle best predicts the maximal exercise capacity in patients with EA.
Keywords: Cardiac function; Cardiovascular magnetic resonance; Ebstein’s anomaly; Exercise capacity; Hemodynamic parameters.